| 摘要 |
PURPOSE:To sufficiently correct aberrations by providing the first area which has a convex and consists of a uniform medium, the second area which is brought into contact with the first area on the side opposite to the convex and has a refractive index distribution in the direction approximately vertical to the optical axis, and the third area which is brought into contact with the second area on the opposite side of the first area and consists of a uniform medium. CONSTITUTION:Plano-convex lenses 1 and 2 consisting of a uniform medium and an optical member 3 which has a refractive index distribution in the direction approximately vertical to an optical axis AX and has planes in both ends (luminous flux incidence and exit faces) constitute a spherical lens. The plane-convex lens 1 is closely brought into contact with the plane on the opposite side of a light emitting element 4 of the optical member 3, and the face on the side opposite to te light emitting element 4 of the plano-convex lens 2 is closely brought into contact with the plane on the side of the light emitting element 4 of the optical member. Consequently, the light emitting element 4 is closely brought into contact with the convex of the plano- convex lens 2 and a light emission point 4a of the light emitting element 4 is placed near the apex of the convex of the plano-convex lens 2. Thus, the spherical aberration and the coma are corrected.
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